Is Alk stability Key to SPS Health

[Randy Holmes-Farley Verified Community Expert]

Yeah, I found reference to that text, but couldn't find the actual text online. So where are you rounding it off from, and why would you do that? :mad:

It varies a lot and much of the tropical ocean is at 7 dKH due to salinity being above 35 ppt. At exactly 35 ppt, it is in the mid 6's. 2.3 meq/L is a commonly stated value.

 

[erk]

It might be accurate, but how did you check it?

I don't believe your tank uses more than 2-3 ppm magnesium per day max. I'm not convinced most gorgonia are high users of magnesium (despite their skeletons being made of "high-magnesium calcite") just because they do not deposit a lot of skeletal material. Typical skeleton ratios of magnesium to calcium in such gorgonia are 0.05 to 0.1 ppm (see link below), which is not higher than coralline algae. To drop 3 ppm per day with one of these at 0.1, you'd need to see a drop of 30 ppm per day calcium and 4 dKH per day alkalinity. Same for a typical coralline algae.

https://www.researchgate.net/profil...7006da4dcef000000.pdf?origin=publication_list

Then I have no idea what is consuming the Mg. There is no scale on the heater or pumps. Maybe the concentration of the current ESV Mg solution is lower than normal.

As for checking the accuracy of the Red Sea kit, I created a solution with a set concentration of Mg from ESV Mg solution that I calculated. Then measured the solution with the Red Sea kit. The Red Sea kit and the calculation matched. I verified that my calculation was correct in a post awhile back just to make sure. It is a simple calculation after all. The kit may be off now since I checked it several months ago. I'll get a new Red Sea kit to check.

If there is something that can act as a sink for Mg, I'd like to know. I dose vodka and have a lot of bacteria growth, but I can't imagine bacteria using a lot of Mg. As I stated before, I don't run any media reactors. No carbon or GFO. Just vodka and a skimmer for nutrient control. I started dosing supplements because I was starving my corals. Since dosing supplements, my corals have improved. Well, until my recent bout of alk solution becoming contaminated and turning brown for some odd reason. But I rectified that issue and things are returning to normal.

 

[Cory]

Then I have no idea what is consuming the Mg. There is no scale on the heater or pumps. Maybe the concentration of the current ESV Mg solution is lower than normal.

As for checking the accuracy of the Red Sea kit, I created a solution with a set concentration of Mg from ESV Mg solution that I calculated. Then measured the solution with the Red Sea kit. The Red Sea kit and the calculation matched. I verified that my calculation was correct in a post awhile back just to make sure. It is a simple calculation after all. The kit may be off now since I checked it several months ago. I'll get a new Red Sea kit to check.

If there is something that can act as a sink for Mg, I'd like to know. I dose vodka and have a lot of bacteria growth, but I can't imagine bacteria using a lot of Mg. As I stated before, I don't run any media reactors. No carbon or GFO. Just vodka and a skimmer for nutrient control. I started dosing supplements because I was starving my corals. Since dosing supplements, my corals have improved. Well, until my recent bout of alk solution becoming contaminated and turning brown for some odd reason. But I rectified that issue and things are returning to normal.

Maybe there is something in your alk solution precipitating magnesium? What kind is it?

 

[erk]

Maybe there is something in your alk solution precipitating magnesium? What kind is it?

I use ESV 2 part and ESV Mg.

 

[wowkingjames]

Interesting, thanks for the info.

 

[Cory]

I use ESV 2 part and ESV Mg.

If you want you can put in 1 liter of water a ml of the mag solution and test its claimed potency with your test kit.

Not sure how much esv has in it

 

[erk]

If you want you can put in 1 liter of water a ml of the mag solution and test its claimed potency with your test kit.

Not sure how much esv has in it

I have done this before. I did it to test the accuracy of the Red Sea kit.

 

[Randy Holmes-Farley Verified Community Expert]

If there is something that can act as a sink for Mg, I'd like to know

Aside from precipitating calcium carbonate that incorporates some magnesium, there is no other significant sink in any reef tank.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, testing a magnesium kit in a pure magnesium solution is not very definitive. It needs to distinguish magnesium from very similar ions such as calcium, and so a magnesium test in seawater is more complex than in a magnesium solution. A seawater standard with known magnesium is the way to go.

 

[Cory]

If you have all the big 2 parameters (cal,alk) in the middle of their maximum and minimum ranges, anything lower or higher than 30% is going to cause problems.

For example:

The lowest for alk is 7dkh. The highest is 11dkh. If you keep it at 9dkh and increase alk 30% youll be at 11.7dkh, which may cause problems. The same with 30% less = 6.3dkh

For calcium the lowest is at 380 and the highest is at 550. If you keep it at 465ppm then 30% more it will be at 604.5ppm. Thats too much. Same reversed you have 325.5ppm calcium which is too low.

The key is to keep it in the middle of the max and min ranges.

 

[bluegrassreefguy]

So I haven't done a water change this week and these are my levels
Cal 460
Alk 7
Mag 1360
Am 0
Nitrate 20
Nitirite 0
Ph 8.2
Sal 1.025
Temp 78.6
I have brs 2 part ready to be mixed up as well as another company's 2 part

I just added some sps this week and switched to metal halides just trying to figure out the best solution

 

[bluegrassreefguy]

 

[Randy Holmes-Farley Verified Community Expert]

So I haven't done a water change this week and these are my levels
Cal 460
Alk 7
Mag 1360
Am 0
Nitrate 20
Nitirite 0
Ph 8.2
Sal 1.025
Temp 78.6
I have brs 2 part ready to be mixed up as well as another company's 2 part

I just added some sps this week and switched to metal halides just trying to figure out the best solution

Doesn't look like you need to add much.